The ACRIMSAT Mission will measure Total Solar Irradiance (TSI) during
its five-year mission life. The ACRIMSAT spacecraft, carrying the
ACRIM III instrument, will be secondary payload on a Taurus vehicle
scheduled to launch in December 1999. The instrument, third in a
series of long-term solar-monitoring tools built for NASA by the
Jet Propulsion Laboratory, will continue to extend the database first
created by ACRIM I, which was launched in 1980 on the Solar Maximum
Mission (SMM) spacecraft. ACRIM II followed on the Upper Atmosphere
Research Satellite (UARS) in 1991.
The Active Cavity Radiometer Irradiance Monitor (ACRIM) I instrument
was the first to clearly demonstrate that the total radiant energy
from the sun was not a constant. However, the solar variability was
so slight (0.1% of full scale) that continuous monitoring by state-of-the-art
instrumentation was necessary. It is theorized that as much as 25%
of the anticipated global warming of the earth may be solar in origin.
In addition, seemingly small (0.5%) changes in the TSI output of
the sun over a century or more may cause significant climatological
changes on earth.
The ACRIMSAT mission is funded by NASA through the Earth Science
Programs Office at Goddard Space Flight Center. The ACRIMSAT Project
Office at the Jet Propulsion Laboratory (Pasadena, CA) manages the
design, fabrication, and test of the ACRIM III instrument and manages
the subcontract for the ACRIMSAT spacecraft being built by Orbital
Sciences Corporation. The ACRIM III data products will be available
through the Langley EOS Data Analysis and Archive Center.
The Principal Investigator for the ACRIM mission is Dr.
Richard Willson of ACRIM Experiments, a sole proprietorship. Sandy
Kwan of the Jet Propulsion Laboratory is the ACRIM Project
Manager. (Other personnel are listed on
the Contact List on the